A renal biopsy is generally recommended for diagnosis and is necessary for classification of lupus nephritis (LN), but second biopsies after immunosuppressive therapy are seldom a routine procedure. We investigated how repeat biopsies contribute to the evaluation of treatment response and long-term outcome in LN.

Sixty-seven patients with active LN were included. Renal biopsies were performed at diagnosis and after standard induction immunosuppressive therapy in all patients (median 8 months), regardless of clinical outcome. Biopsies were evaluated according to the International Society of Nephrology/Renal Pathology Society classification. Clinical response was defined as complete (CR), partial (PR) or non-response (NR) according to recent definitions. Histological response (HR) was defined as Class I, II or III/IV-C on repeat biopsies. Long-term renal outcome was determined in 55 patients after a median of 10 years.

CR was demonstrated in 25%, PR in 27% and NR in 48% of patients. HR was shown in 42% and histopathological non-response (HNR) in 58% of patients. Twenty-nine per cent of CR and 61% of patients with PR had active lesions on repeat biopsies, that is, were HNR. Poor long-term renal outcome was associated with high chronicity index at repeated biopsies, but not with clinical or histological response.

Despite apparent clinical response to immunosuppressive therapy, repeated biopsies revealed persisting active nephritis in almost half of the patients, thus providing additional information to clinical response criteria. Repeated renal biopsies may be a tool to improve the evaluation of treatment response in LN.